Phosphatidylinositol 3-kinase mediates chemoattractant-stimulated, CD11b/CD18-dependent cell-cell adhesion of human neutrophils: evidence for an ERK-independent pathway.
We examined the role of phosphatidylinositol 3-kinase (PI 3-K) in FMLP-stimulated cell-cell adhesion of human neutrophils. The specific PI 3-K inhibitors wortmannin and LY294002 inhibited neutrophil homotypic aggregation stimulated by chemoattractants such as FMLP (50% inhibitory concentration (IC50) approximately 11 nM and 13 microM, respectively) but not PMA. Wortmannin also inhibited FMLP-stimulated adhesion of neutrophils to human endothelial cell monolayers, suggesting a common signaling pathway for homotypic and heterotypic adhesion. Neither CD11b/CD18 expression nor expression of an activation-specific epitope of CD11b/CD18 was affected by wortmannin in FMLP-stimulated cells. Moreover, wortmannin also inhibited the aggregation of egranulate neutrophil cytoplasts that lack the capacity for CD11b/CD18 up-regulation. Although wortmannin inhibited neutrophil lysosomal enzyme release, it had no effect on FMLP-stimulated up-regulation of CD35 in intact neutrophils, suggesting discrepant signaling pathways for specific granule degranulation and secretory vesicle release. Aggregation of human neutrophils is associated with activation of the mitogen-activated protein kinases Erk1 and -2, and Erk is activated in response to PI 3-K in some cell types. However, wortmannin inhibited FMLP stimulation of neutrophil Erk only at concentrations (IC50 > or = 1 microM) inconsistent with an effect on PI 3-K. Our data indicate that PI 3-K mediates neutrophil adhesion by a mechanism independent of CD11b/CD18 up-regulation, suggesting that PI 3-K acts either parallel to, or downstream of, Erk.
Capodici
C
C
Department of Medicine, New York University School of Medicine 10016, USA.
Hanft
S
S
Feoktistov
M
M
Pillinger
M H
MH
D000730:Androstadienes / Q000494:pharmacology; D018821:CD18 Antigens / Q000096:biosynthesis / Q000502:physiology*; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000502:physiology*; D002448:Cell Adhesion / Q000187:drug effects / Q000276:immunology; D002449:Cell Aggregation / Q000187:drug effects / Q000276:immunology; D002461:Cell Line, Transformed; D002867:Chromones / Q000494:pharmacology; D015936:Complement C5a / Q000037:antagonists & inhibitors / Q000502:physiology; D004730:Endothelium, Vascular / Q000187:drug effects / Q000276:immunology; D000939:Epitopes / Q000096:biosynthesis; D006801:Humans; D007476:Ionophores / Q000494:pharmacology; D016177:Macrophage-1 Antigen / Q000096:biosynthesis / Q000502:physiology*; D009025:Morpholines / Q000494:pharmacology; D009113:Muramidase / Q000037:antagonists & inhibitors / Q000378:metabolism; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D018375:Neutrophil Activation / Q000276:immunology; D009504:Neutrophils / Q000187:drug effects / Q000201:enzymology / Q000276:immunology*; D019869:Phosphatidylinositol 3-Kinases / Q000502:physiology*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D015854:Up-Regulation / Q000187:drug effects / Q000276:immunology; D000077191:Wortmannin
D000730:Androstadienes; D018821:CD18 Antigens; D002867:Chromones; D000939:Epitopes; D007476:Ionophores; D016177:Macrophage-1 Antigen; D009025:Morpholines; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; D009240:N-Formylmethionine Leucyl-Phenylalanine; D015936:Complement C5a; D019869:Phosphatidylinositol 3-Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D009113:Muramidase; D013755:Tetradecanoylphorbol Acetate; D000077191:Wortmannin